JP3728086B2 - Anticorrosion reinforced concrete assembly and assembly method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an anticorrosion reinforced concrete assembly, and an anticorrosion method and an assembly method thereof.
[0002]
[Prior art]
In concrete structures such as a reinforced concrete (RC) structure and a prestressed concrete (PC) structure, corrosion of the reinforcing steel or steel material occurs due to permeation of oxygen, water, chloride ions, and the like. When steel materials and the like are corroded, cracks occur in the concrete due to the corrosion products, further accelerating the corrosion and finally reducing the strength and the like of the concrete structure.
[0003]
As an extremely effective method for preventing corrosion of steel materials and the like in a concrete structure, there is an anticorrosion method. The anti-corrosion method is to stop the corrosion by changing the metal to an electrochemically stable potential region. In particular, in concrete structures, the potential of steel in the concrete structure is forced by an external power source. This means that the corrosion of steel materials and the like is stopped by changing the temperature. In other words, the anode reaction (oxidation reaction) and the cathode reaction (reduction reaction) occur simultaneously on the surface of the steel material or the like in the concrete structure in a state where the potential is not changed, and a corrosion cell is formed as a result. Corrosion occurs due to the occurrence of corrosion, etc., but by changing the potential of the steel material, only the cathode reaction can occur on the surface of the steel material, thereby preventing the generation of iron hydrated oxides, etc. can do.
[0004]
In order to carry out the cathodic protection method, an anode is generally provided on the concrete surface, while steel or the like is used as the cathode. As a result, current is supplied to the steel material through the concrete to change the potential of the steel material in the base direction, thereby realizing corrosion prevention.
[0005]
The material of the anode provided on the concrete surface is required to have performance such as high electrical conductivity, excellent stability, durability and economy, and simple construction. As the anode that is currently in practical use, titanium wire, zinc, carbon fiber wire, etc. with a platinum metal oxide coated on the surface are used.
[0006]
However, when anticorrosion is performed using these linear anodes, the potential distribution is uneven on the concrete surface, and the voltage at the portion where the concrete surface and the electrode are in contact with each other increases, so that chlorine gas is generated. Problems occur.
[0007]
In addition, when repairing a concrete structure with corroded steel, etc., in order to reinforce its proof stress, an anti-corrosion device is also provided, and after the repair, the anti-corrosion is performed to further corrode the steel. Is done to stop. However, in the current situation, the process of providing such a device for cathodic protection is performed separately from the repair for reinforcing the strength of the conventional concrete structure.
[0008]
[Problems to be solved by the invention]
The object of the present invention is to provide a uniform electric potential distribution on the surface of the concrete when performing anticorrosion, to reduce the generation of chlorine gas, etc., and to achieve corrosion prevention without increasing the voltage to be energized, and the strength and the like. An object of the present invention is to provide an excellent concrete assembly.
[0010]
Another object of the present invention is to reinforce an existing concrete structure by a simple method, uniform the potential distribution on the concrete surface, reduce the generation of chlorine gas, etc., and increase the energizing voltage. An object of the present invention is to provide a method for assembling an anti-corrosion reinforced concrete assembly, which makes it possible to perform anti-corrosion that can be prevented without corrosion.
[0011]
[Means for Solving the Problems]
According to the present invention, a concrete structure including concrete and a steel material provided in the concrete, a conductive adhesive provided on the surface of the concrete structure, and carbon fibers are extended in the length direction of the sheet. Conductive part for anode comprising a carbon fiber sheet having a volume resistivity of 5 × 10 ⁻⁴ to 1 × 10 ⁻³ Ω · cm or an adhesive-impregnated carbon fiber sheet provided with the carbon fiber sheet. And an energization means connected to the steel material and an end of the carbon fiber sheet of the anode conduction portion, the steel material as a cathode of the energization means, and the anode conduction portion as an anode of the energization means An anticorrosion reinforced concrete assembly connected to is provided.
[0013]
Furthermore, according to the present invention, on the surface of an existing concrete structure including concrete and steel material provided in the concrete , the volume resistivity is 5 × , which is arranged by extending carbon fibers in the length direction of the sheet. 10 ⁻⁴ to 1 × 10 ⁻³ Ω · cm, a carbon fiber sheet is pasted via a conductive adhesive, and a conductive part for anode composed of the conductive adhesive and the carbon fiber sheet is provided, and the steel material is The method for assembling the anticorrosion reinforced concrete assembly according to claim 1, wherein the current-carrying means is connected so as to serve as a cathode and an end of the carbon fiber sheet of the anode conducting portion as an anode.
Furthermore, according to the present invention , the volume resistivity is 5 on the surface of an existing concrete structure including concrete and a steel material provided in the concrete , the carbon fibers being extended and arranged in the length direction of the sheet. A carbon fiber sheet of × 10 ⁻⁴ to 1 × 10 ⁻³ Ω · cm is pasted through a conductive adhesive, and the pasted carbon fiber sheet is impregnated with an impregnation adhesive, An anode conducting portion comprising an adhesive-impregnated carbon fiber sheet is provided, and the energizing means is connected so that the steel material serves as a cathode and the end of the carbon fiber sheet of the anode conducting portion serves as an anode. A method for assembling the anti-corrosion reinforced concrete assembly according to claim 1 is provided.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
The anticorrosion reinforced concrete assembly of the present invention includes a concrete structure including concrete and a steel material provided in the concrete.
[0015]
The concrete includes not only ordinary concrete including cement, water, fine aggregate, coarse aggregate, and the like, but also hardened mortar, cement paste, and the like.
[0016]
The steel material refers to a metal widely provided in concrete, and includes a metal provided in concrete for the purpose of enhancing the durability of the concrete, such as a reinforcing bar provided in RC and a steel material provided in PC. .
[0017]
The anticorrosion reinforced concrete assembly of the present invention has a volume resistivity of 5 × 10 ^{−4, which} is formed by extending a carbon fiber in the length direction of the sheet and a conductive adhesive provided on the surface of the concrete structure. It includes a conductive part for an anode comprising a carbon fiber sheet or an adhesive-impregnated carbon fiber sheet provided with the carbon fiber sheet, which is ˜1 × 10 ⁻³ Ω · cm.
[0018]
The carbon fiber sheet includes carbon fiber and has a shape in which the potential distribution on the attached surface is uniform when used as an anode when performing anticorrosion. Specifically, it is a sheet in which 10 million or more carbon fibers having a diameter of 7 to 10 μm extending in the length direction of the sheet are arranged and woven per 1 m in the width direction, and the thickness is 0.05 to 0.2 mm. Can be mentioned. As such a carbon fiber sheet, for example, “TU cloth” (trade name, manufactured by Nippon Oil Co., Ltd.) can be used.
[0020]
Tensile strength of the carbon fiber sheet is about 30,000kgf / cm ² or more, particularly about 35,000~72,000kgf / cm ² or more and a tensile modulus of elasticity of about 2.35 × 10 ⁶ ~8.00 × 10 ⁶ kgf / cm ² is preferable because a high strength anticorrosion reinforced concrete assembly can be obtained.
[0021]
The carbon fiber sheet is preferably provided on the surface of the concrete structure such that the tensile strength of the carbon fibers is in a direction to reinforce the concrete structure. Furthermore, in order to achieve sufficient reinforcement, two or more layers of carbon fiber sheets can be provided on the concrete structure surface as necessary.
[0022]
The aspect of providing the carbon fiber sheet on the surface of the concrete structure is not particularly limited as long as the current can be distributed on the surface of the concrete, but it may be applied to the surface of the concrete structure with a conductive adhesive. It is preferable because conductivity can be secured while reinforcing the structure.
[0023]
The conductive adhesive has a volume resistivity of 10 Ω · cm or less when cured, and an adhesive strength of 20 kgf / cm ² or more can be obtained between the concrete surface and the carbon fiber sheet when cured. preferable.
[0024]
Specific examples of the conductive adhesive include a resin such as an epoxy resin containing conductive powder such as silver and carbon. The content of the powder in the resin is preferably 60 to 90% by weight.
[0025]
Further, when the carbon fiber sheet is provided on the surface of the concrete structure, the carbon fiber sheet is pasted on the surface of the concrete structure with the conductive adhesive, and then another impregnation adhesive is added in the fiber. It is preferable that the carbon fiber sheet is impregnated with an adhesive so that the adhesive strength and durability of the carbon fiber sheet can be improved. Examples of the other adhesive for impregnation include epoxy resins.
[0026]
The anticorrosion reinforced concrete assembly of the present invention includes energization means connected to the steel material and the anode conducting portion .
[0027]
The energization means is not particularly limited as long as it can supply an anticorrosion current, and various DC stabilized power supply devices such as commercially available ones can be used.
[0028]
The connection of the energizing means to the steel material is performed by connecting the energizing means to a drain terminal provided by connecting a coated lead wire to the steel material by spot welding, screwing or the like, for example. it can.
[0029]
The connection of the energizing means to the anode conducting portion can be performed by connecting the energizing means with a lead connected to the end of the carbon fiber sheet by screwing or the like.
[0030]
The anti-corrosion reinforced concrete assembly of the present invention can include a reference electrode for adjusting the anti-corrosion current amount in the anti-corrosion and confirming the rebar potential for confirming the anti-corrosion effect, if necessary. As the reference electrode, a silver chloride electrode or a lead electrode can be used. The reference electrode is preferably provided in the vicinity of the steel material in the concrete structure.
[0031]
The anticorrosion reinforced concrete assembly of the present invention can be assembled when constructing a new concrete structure, but as a repair of the existing concrete structure, the carbon fiber sheet is conductively bonded onto the surface of the existing concrete structure. Attaching via an agent, provided with a conductive portion for the anode consisting of a conductive adhesive and an adhesive-impregnated carbon fiber sheet, and a means for energizing the steel material in the existing concrete as the cathode and the anode conductive portion as the anode It can also be assembled by connecting.
[0032]
When assembling the anticorrosion reinforced concrete assembly of the present invention as a repair of an existing concrete structure, prior to the application of the carbon fiber sheet, a drain terminal or the like is provided on the steel material in the concrete structure, and the concrete structure It is preferable to provide the reference electrode. Moreover, it is preferable to confirm whether all the steel materials in the concrete structure are electrically connected and to conduct the steel materials by welding or the like as necessary. Then, it is preferable to perform a treatment such as removing dirt, latency, etc. adhering to the surface of the concrete structure by sandblasting, ultra-high pressure water jet or the like, and further removing concrete powder with compressed air.
[0033]
The carbon fiber sheet is attached to the surface of the dried concrete structure by uniformly applying the conductive adhesive with a roller brush or a rubber spatula, and then immediately adhering the carbon fiber sheet, and then the surface of the sheet with a rubber spatula or the like in the fiber direction. It can be carried out by ironing and further impregnating the adhesive for impregnation.
[0034]
The corrosion process of corrosion reinforced concrete assembly of the present invention, the conductive portion for the anode and cathode steel material of the corrosion reinforced concrete assembly is energized to an anode.
[0035]
Since the preferable energization amount at the time of energization varies depending on the structure of the anticorrosion reinforced concrete assembly, etc., it is preferably determined by an energization test. Specifically, it can be determined by the following procedure.
[0036]
1) The natural potential of the steel material is measured.
[0037]
2) Obtain the relationship between the amount of energized current and the potential of the steel material by a polarization test.
[0038]
3) An energization current amount for obtaining a required polarization amount from a natural potential is obtained.
[0039]
4) Energize for 24 hours or longer with the energization current obtained in 3).
[0040]
5) It is confirmed whether a predetermined depolarization amount (100 mV or more) can be obtained by a depolarization test.
[0041]
【The invention's effect】
Since the anticorrosion reinforced concrete assembly of the present invention has a specific structure, the electric potential distribution on the surface of the concrete becomes uniform when performing anticorrosion, the generation of chlorine gas and the like can be reduced, and the energized voltage is increased. Even if it is not, corrosion prevention is achieved and the concrete assembly is excellent in strength and the like.
[0043]
The method for assembling the anticorrosion reinforced concrete assembly of the present invention is an assembling method in which a specific structure is provided in the existing concrete structure and the specific anticorrosion reinforced concrete assembly is used. When conducting, the potential distribution on the surface of the concrete becomes uniform, the generation of chlorine gas, etc. can be reduced, corrosion prevention is achieved without increasing the energizing voltage, and repair is made as a concrete assembly with excellent strength etc. be able to.
[0044]
【Example】
Hereinafter, although an Example demonstrates further in detail, this invention is not limited to these.
[0045]
As shown schematically in FIG. 1, an existing reinforced concrete structure was provided with a carbon fiber sheet, a power supply device, and the like, and an anticorrosion reinforced concrete assembly 1 was assembled.
[0046]
First, as an anode pre-treatment process, an existing reinforced concrete 3 (length 2.25 m, width 1.99 m, thickness 0.21 m, and D19 rebar ST345 extending in the length direction is covered with a cover of 30 mm and a pitch of 150 mm. The deteriorated part of the RC bridge floor plate) was removed, the surface metal of the concrete was removed, and the surface of the concrete was treated with cement paste. Lead wires were connected to the reinforcing bars 2 in the concrete by spot welding, and discharge terminals 9 and measurement terminals 12 were provided. Furthermore, the silver chloride reference electrode 10 was fixed to the reinforcing bar with a plastic band. Further, whether or not all the reinforcing bars 2 existing in the concrete structure are electrically connected was measured, and if there was a non-conductive reinforcing bar, it was welded and connected to make all the reinforcing bars conductive.
[0047]
Next, as anode installation work, dirt, latency, etc. adhering to the bottom surface of the concrete structure 3 were removed by sandblasting, ultra-high pressure water jet, etc., and concrete powder was removed by compressed air. After the concrete surface is dried, the carbon epoxy conductive adhesive 4 (a mixture of epoxy resin: carbon powder = 2: 8) is uniformly applied to the concrete surface with a roller brush or rubber spatula, and immediately thereafter a carbon fiber sheet ( A product name “TU cloth” (manufactured by Nippon Oil Co., Ltd.) 5 is pasted, and the sheet surface is rubbed with a rubber spatula in the fiber direction. )) Was impregnated into the fibers. After connecting the end portion of the carbon fiber sheet to the lead 7 by screwing, it was confirmed that the installed carbon fiber sheet anode was electrically connected using a DC voltmeter.
[0048]
Further, as a corrosion prevention circuit forming work, a power supply box for storing the DC power supply device 8 was fixed to a concrete base with an anchor bolt. These were connected to the DC power supply 8 so that the discharge terminal 9 was on the cathode side and the lead wire 7 was on the anode side. All wires and connection points for connection were treated with an insulating material and a waterproof material.
[0049]
The thus formed anticorrosion reinforced concrete assembly of the present invention was subjected to a polarization test using the DC power supply 8 and the voltmeter 11, and a required polarization amount (100 mV or more) was obtained at 10 mA / m ^2. I understood that.
[0050]
Energization was performed for 1 hour with this energization amount. During energization, generation of chlorine gas was not observed on the anode surface. Further, a depolarization test was conducted after 24 hours of energization, and it was confirmed that a depolarization amount of 100 mV or more was obtained.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an example of an anticorrosion reinforced concrete assembly of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1; Corrosion-proof reinforced concrete 2; Reinforcement 3; Reinforced concrete structure 4; Conductive adhesive 5; Carbon fiber sheet 8; Power supply device 9; Exhaust terminal 10;

Claims (3)

A concrete structure including concrete and a steel material provided in the concrete;
The volume resistivity is 5 × 10 ⁻⁴ to 1 × 10 ⁻³ Ω · cm , which is formed by extending the carbon fiber in the length direction of the sheet and the conductive adhesive provided on the surface of the concrete structure. A conductive portion for an anode comprising a carbon fiber sheet or an adhesive-impregnated carbon fiber sheet provided with the carbon fiber sheet, and the steel material and the end portion of the carbon fiber sheet of the conductive portion for anode. An anti-corrosion reinforced concrete assembly including the energizing means, wherein the steel material is connected to the cathode of the energizing means, and the anode conducting portion is connected to the anode of the energizing means. A volume resistivity of 5 × 10 ⁻⁴ to 1 × 10 is obtained by extending carbon fibers in the length direction of the sheet on the surface of an existing concrete structure including concrete and a steel material provided in the concrete. ^-3 Ω · cm, a carbon fiber sheet pasted through a conductive adhesive, provided with a conductive part for an anode made of a conductive adhesive and a carbon fiber sheet, the steel material as a cathode, and the conductive part for an anode The method for assembling the anticorrosion reinforced concrete assembly according to claim 1, wherein the energizing means is connected so that the end of the carbon fiber sheet is an anode. A volume resistivity of 5 × 10 ⁻⁴ to 1 × 10 is obtained by extending carbon fibers in the length direction of the sheet on the surface of an existing concrete structure including concrete and a steel material provided in the concrete. ^-3 Ω · cm, a carbon fiber sheet is pasted through a conductive adhesive, and the impregnated adhesive is impregnated into the pasted carbon fiber sheet, from the conductive adhesive and the adhesive-impregnated carbon fiber sheet. 2. An anti-corrosion reinforced concrete set according to claim 1, further comprising: a conductive portion for anode, wherein the current-carrying means is connected so that the steel material is a cathode and an end of the carbon fiber sheet of the anode conductive portion is an anode. Solid assembly method.

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